#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 5e5 + 5;

int n, m;
int a[N];

int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n;
  rep(i, 1, n) cin >> a[i];
  int r = 1;
  ll ans = 0;
  rep(i, 1, n) {
    while (r <= n && a[r] < a[i] * 2) r++;
    ans += n + 1 - r;
  }
  cout << ans;
  return 0;
}